Trouble with seized fill/drain plugs

Just tell a dealership parts department what you need?

 

Possibly many of us have learned that buying from any dealership parts dept. involves them selling you a bolt for $12.59 that was sourced from China for 7c. Now $12.59 may not break your wallet, but it sure feels bad when you know this. And many people will go to considerable lengths to avoid this.

 

Any drain plug having an M18x1.5 thread pitch will work. On Amazon, you could purchase them in steel, aluminum and stainless steel.

I prefer aluminum with neodymium magnets.

 

The drain for the inverter is on the radiator, works the same way. And plastic.
If you striped that out, you'll be looking at a new radiator...

The transmission ones are metal.

 

On the Gen 3 Prius, the inverter coolant drain is not on the radiator. It is on the bottom of the inverter. It uses exactly the same plug as those on the inverter drain and fill transaxle fluid ports.



The Prius C has the inverter drain on the hose as does the Gen 4, both of which use the same type of yellow winged plastic plug with an O ring seal as the radiator,

 

Brain fart on my part!

 

These are steel M18x1.5 with 19mm hex heads and aluminum washers and will fit perfectly on the Gen 3 Prius transaxle. Nice thing is that they are only $8.49 on Amazon.

X AUTOHAUX 5 Sets M18x1.5mm Metal Car Engine Oil Pan Drain Cap Screw Bolt Plug with Gasket

I purchased a set myself and can assure anyone interested that they will fit.

 

I use a Honda oil filter wrench (prefer to call it a socket, seems more to the point). In my experience Honda, Toyota and Mazda all have the same oil filter dimensions.

the Honda oil filter socket is heavy gauge stamped steel. Back in the eighties their automotive division used a larger oil filter, and the current size was only used on their motorcycles. I had one of each oil filter sockets.

maybe in the nineties they adopted the motorcycle oil filter into their cars. Anyway, still using that same (originally purchased for Honda motorcycle) oil filter socket, indestructible, currently on those 3 makes.

you can likely get one through any Honda dealership, also available on Amazon.

addendum: looks pricey on Amazon right now, believe this is it:

Genuine Honda Oil Filter Wrench (65mm) - 07AAA-PLCA100

part no indicated in above:

07AAA-PLCA100

again, local Honda dealership parts department is likely best bet for sourcing this.

 

...these old plugs were used on all older toys like 70 80 w 5 trans rear diffs etc . Tool box have a few in they're too .that m18 was real popular.

 

Yep, those transmission drain/fill plugs can be a PITA to get to break free. In 2020, my daughter bought a used Sienna (2012) with 140,000 miles on it. After I looked it over, I debated NOT changing out the transmission fluid because, at that age/miles, sometimes changing out the fluid can do more harm than good. But it didn't took too burnt so I went ahead and did the service.
Removing those drain/fill bolts did, probably, take about 130 ft/lbs and I didn't spray any penetration oil on there. When you put on the hex socket, give it a few wacks of the hammer which helps to seat it and, also, can jar the threads a bit which can help them break free.
If it doesn't break free, go ahead and spray it with pen lube and let it sit for an hour or so. (I like good old bolt blaster.) I've done a LOT of cars and never had to drill one out or use heat on them....thank Goodness! Having replacement bolts, also, gives you confidence to go ahead and tug hard on the thing.

 

I’ve also heard “shock the threads”. This is what an impact wrench does, with a series of hammer-like, rapid-fire, counterclockwise twists on the bolt head. A physicist would maybe use the term inertia? You hit something so fast it’s surroundings stay in place, and that something is gone.

I was trying to break loose exhaust bolts recently, and my cheapie, corded electric impact wrench finally did the trick. Had to hold it on a few seconds, and the rapid-fire impacts slowly got it turning.

another trick would be to heat the surrounding metal, say with a propane plumbers torch, then quickly hit the bolt. The heat will expand the surrounding metal slightly. Though aluminum casing of the transaxle, filled with coolant, may make that a bust; too difficult to heat effectively.

 

There's also a kind of tool called a "seized fastener removal kit" that works with an air hammer.

Where the familiar impact socket driver is applying high impact torque in the rotating direction, these seized-fastener tools just apply air-hammer impacts, couple thousand a minute, straight down on the fastener while you apply normal steady torque to turn it. I have found them to work really well, especially on smaller stuck fasteners where high impact torque would probably just break or strip them.

Either way, it's the rapid blows shaking loose the threads that have stuck to each other, and the twisting torque that then unscrews the thing.

 

Glad you, at least, got that tranny plug off. I've, also, heard a "pop" sound as the sucker finally broke free!

In my Gen 4 Prius, we just use two plastic drain cocks on the radiator (one is yellow and one is white) to drain the coolant from the radiator and traction system. The Car Care Nut, on YouTube does have a video of him breaking the drain bolt on the bottom and it look like it was quite stuck...he's a pretty strong guy so got it off, and did make a pop sound.

 

I thought of this thread this weekend as I had my son-in-laws old 2008 Rav4 getting her maintenance caught up. I noticed the front differential fluid had not been changed so I had a few qts of 75W-90 gear oil so decided to do the job. That 24mm fill plug was so tight I had to get out the big breaker bar and, even then, had to REALLY get brutal with it.....finally it popped free. (I was going to spray some Bolt Blaster pen oil on it, first, but I couldn't find the can...I need to clean out my garage.) The drain plug was, also, tight but it also popped off. Again, I doubt this job had ever been done...the magnet was pretty filled up with small metal debris and it seemed to take quite a bit more than what drained out.

 

Just replace the socket headed hex plugs with hex head plugs, and you'll never have future problems in removing them.

 

Hey, THAT is an excellent idea!! My Tundra is due for her 3-year front/rear/transaxle fluid changes so I'll get those!!

 

$8.50 with aluminum gaskets on Amazon.
X AUTOHAUX 5 Sets M18x1.5mm Metal Car Engine Oil Pan Drain Cap Screw Bolt Plug with Gasket